// 数组find方法
if (!Array.prototype.find) {
  Object.defineProperty(Array.prototype, 'find', {
    value: function (predicate) {
      if (this == null) {
        throw new TypeError('"this" is null or not defined');
      }
      var o = Object(this)
      var len = o.length >>> 0
      if (typeof predicate !== 'function') {
        throw new TypeError('predicate must be a function')
      }
      var thisArg = arguments[1]
      var k = 0
      while (k < len) {
        var kValue = o[k]
        if (predicate.call(thisArg, kValue, k, o)) {
          return kValue
        }
        k++
      }
      return undefined
    }
  })
}